In vivo electroporation of plasmids encoding GM-CSF or interleukin-2 into existing B16 melanomas combined with electrochemotherapy induces longterm antitumour immunity

When cancer cells, including melanoma cells, are genetically altered to sec rete cytokines, irradiated and injected into subjects, long-term antitumour immunity is induced. Optimally, existing melanomas induced to produce cyto kines in vivo could stimulate this same immune response. Although in vivo e lectroporation enhances plasmid expression, electroporation of plasmids enc oding granulocyte-monocyte colony stimulating factor (GM-CSF) and interleuk in-2 (IL2) into B16 mouse melanomas did not significantly alter tumour grow th at the concentration tested. Electrochemotherapy, which causes short-ter m, complete regressions of treated tumour but no resistance to challenge, w as combined with plasmid delivery. The combination treatment resulted in th e induction of long-term immunity to recurrence and resistance to challenge in up to 25% of mice, (C) 2000 Lippincott Williams & Wilkins.